This invention relates to electrocardiography (ECG) and to electrode arrangements used in electrocardiographic monitoring and recording, and is more particularly related to a pad containing said electrodes and a method for passively and non-invasively monitoring or recording the heart's electrical activity from the surface of a patient's chest, and where desired, correlating such ECG recordings with the standard ECG leads I, II and III.
The electrical potential generated by the heart appears throughout the body and on the surface of the body. Such electrical potentials are helpful to physicians in evaluating the heart's condition. Three basic leads, I, II, and III, make up the frontal plane ECG. These are derived from the various permutations of pairs of electrodes with one electrode located on the right arm, one located on the left arm, and one located on the left leg. When physicians examine the ECG in the transverse plane, they utilize chest leads. In this procedure, electrodes are placed at various anatomically defined positions on the chest wall, and are connected to an ECG recorder. These leads are known as precodial ECG leads. The position of these precordial lead electrodes, designated V1 through V6, is as follows: V1 is located on the fourth intercostal space at the right sternal margin; V2 is located on the fourth intercostal space at the left sternal margin; V3 is located midway between electrode V2 and electrode V4; electrode V4 is located on the fifth intercostal space at the mid-clavicular line; electrode V5 is located on the same level as electrode V4 and on an anterior axillary line; and electrode V6 is located on the same level as electrode V4 and on a mid-axillary line.
Because the surface of the heart is in close proximity to the chest wall, each precordial electrode and its accompanying lead primarily records the electrical activity or potential of the cardiac musculature immediately beneath the electrode position. Therefore, to achieve proper results, the medical technician, particularly when measuring ECG, must be careful to place each chest electrode at its precise location on the chest. When using individual electrodes, this procedure can prove to be inconvenient, time consuming and sometimes inaccurate. Furthermore, if for some reason an precordial ECG recording has to be repeated on the same patient, the probability of locating individual electrodes at the same position is slight. Additionally, the large diameters of convential ECG electrode bodies often results in over lapping of the electrode bodies further complicating proper positioning.
Another use of electrodes is the monitoring of heart activity in intensive care patients who have suffered cardiac problems such as myocardial infarction. In this procedure, three electrodes are placed on the chest of the patient. One is placed in the area of the left shoulder, one in the area of the right shoulder, and one at the end of the sternum.
U.S. Pat. No. 4,328,814 issued May 11, 1982 to Arkens discloses a precordial ECG strip in which individual electrodes are physically connected to one another through bundled conductors terminating in a connector block. Although perhaps more convenient than separate electrodes, this invention also requires the medical technician to individually place each of the six electrodes on the body of the patient, thereby consuming valuable time and making repeatability of measurement subject to inaccuracies because of improper placement. The bundling of conductors in this invention does not materially improve positioning of the electrodes, as each must be individually placed onto the patient's chest. The invention also may be subject to interference and artifact problems because of the close proximity of the bundled conductive leads between electrodes. Further, the plug connector utilized to connect the electrodes with an ECG recorder is not standard within the medical community.